Woah Nelly, I got a horse in this race

The first time I met my future mother-in-law we had to move 10 or so horses an hour from one farm to another in a 3 horse trailer. All of the tac lockers and gear had to move too and I am a fantastic pack animal if nothing else. It was an interesting evening but if you ever want to leave a good impression, you should try it. I also lost my arachnophobia since I didn’t want to scream like a toddler every time I came across the devil incarnate. Still hate spiders, but I only shoot once now. 

What was the point of that? Horses. Zoonotic diseases were a common talking point of the masses after COVID-19 started its world tour. The same thing happened after Ebola’s debut on the scene, when HI  pulled a Cool-aid man wall smash out of primates, and after the MERS pulled a Snake Plissken and escaped dromedaries like he escaped New York. But we have an extremely short memory so really, who remembers those events? What events? What was I talking about? Oh hi my name is John and this is my blog. What is it called?

I know I waffle on, deal with it. Hendra virus is in the game genus as Nipah virus and same family as human parainfluenza virus, measles, and mumps. Grow up in that family and I don’t blame Hendra for being deadly. Kinda like having Bugsy Siegel as an uncle. Enough bull crap, or in this case horse crap. Actually flying fox urine. Hendra virus is endemic in almost 50% of flying foxes down under and causes a viremia, in turn leading to virus laden urine. Since no one ever potty trained bats they tend to pee everywhere, especially when hanging out in trees. If the horses graze under those trees, you now have Hendra horses. 

My question is what about other animals? Flying foxes eat fruit and drop their leftovers covered in saliva an excrement (hope you’re not eating any fruit right now). Won’t other animals get infected? Cats, mice, Guinea pigs, and dogs have also been infected in labs, only dogs have been found with Hendra antibodies in the wild (at least what I found). Regardless, we humans get Hendra from horses in all known cases. When horses get sick they tend to develop respiratory symptoms and meningitis with accompanying neurological symptoms. 

The virus is transmitted to humans via respiratory droplets from infected animals, or bat urine. Pro tip: don’t breath around horses and don’t drink bat piss. The first outbreak in 1994 led to the death of one person and 14 horses. Retrospective analysis of samples from other animals showed no evidence of prior infections. So maybe that was the first jump from bats? Maybe, probs not. The world is big and old with nothing new under the Sun. Don’t mistake that as old equals boring, that ain’t the case buddy. 

This virus binds to respiratory epithelium cells and cause havok via inflammation and the immune response. Which in turn disrupts the blood-brain barrier leading to aseptic meningitis and neurological effects, the most prominent of which is death. Or is death a cardiovascular symptom? Anyways, I will now get into some deep water, so please, correct me if I muck this up. One of the cytokines, stuff that cells secret that makes other cells do stuff, (I won't make a joke here) is tumor necrosis factor alpha. At the most basic level, it is released by macrophages to bring other cells to the area causing more inflammation. fun fact, as an adipokine it causes the low grade inflammation seen with obesity. This bugger is blamed for everything from depression to cancer to Alzheimer's disease. I want to learn more about this but that is for another post.

Where was I? Oh yes, inflammation. Be it around the brain or lungs the inflammation causes pressure on structures that do not need the extra pressure. They don't listen to Queen and will not be convinced to like them. Que symptoms of meningitis like headaches, photophobia, and Brudzinski's sign; or respiratory damage like dyspnea, cough, and hypoxia. Fun stuff. 

Ok John but why do you bring this up? To depress us all? Tell me about the treatment! No, I wrote this to scare everyone just before the Hendra virus pandemic begins and kills us all. It's the end of the world, and I feel fine.

No, there are vaccines for horses, ribavirin, and prophylactic Ig. Plus, it isn't all that contagious for people. But it could be, so maybe the point of this is to scare us a little. When we are not careful about how and where we encroach upon nature, bad things can arise that we may not be ready for. Play with fire and get burnt type of thing. There is a find balance to how nature was meant to work and these viruses did not evolve to kill us, though we may be unwitting victims of their internal machinery. This does not mean that they will not evolve to kill us more effectively or spread more rapidly among humans. There are many new things out there and we should learn all we can about them. If COVID did anything it helped grow our knowledge of viruses which could help with future treatments for Hendra and other viruses. Who knows? Alternatively, we are all screwed. Which is more likely. Love y'all. 

References

Emerging tropical diseases in Australia. Part 5. Hendra virus from the Annals of Tropical Medicine and Parasitology 2011 by Tulsiani et al. 

Image of Hendra virus from the Wikipedias.

Pathogenesis of Hendra and Nipah virus infection in humans from the Jounral of Infections in Developing Countries by Escaffre et al. in 2013

Routes of Hendra Virus Excretion in Naturally-Infected Flying-Foxes: Implications for Viral Transmission and Spillover Risk from PLOS One by Edson et al. in 2015. 

The Role of Tumor Necrosis Factor Alpha (TNF-α) in Autoimmune Disease and Current TNF-α Inhibitors in Therapeutics in the International Journal of Molecular Sciences 2021 by Jang et al.